L16 - Sign Test

Question 1

what are the TWO TYPES of STATISTICS?

Answer 1

There are TWO TYPES of STATISTICS, DESCRIPTIVE STATISTICS (measures of CT and D) AND INFERENTIAL STATISTICS.

INFERENTIAL STATISTICS take a SAMPLE OF A TARGET POPULATION and TEST A HYPOTHESIS, if it stands true, then we can INFER that the SAME IS TRUE FOR ALL PEOPLE IN THE TARGET POPULATION

Question 2

how do INFERENTIAL STATISTICS WORK? - PT 1

Answer 2

In order to MAKE AN INFERENCE about our TARGET POPULATION we first have to USE INFERENTIAL STATISTICS to see IF OUR RESULTS ARE SIGNIFICANT

INFERENTIAL STATISTICS are designed to WORK OUT THE PROBABILITY (P) that a PARTICULAR SET OF DATA OCCURRED BY CHANCE, and NOT BECAUSE OF THE INDEPENDENT VARIABLE

Question 3

how do INFERENTIAL STATISTICS WORK? - PT 2

Answer 3

The ACCEPTED LEVEL OF PROBABILITY that a DATA SET has OCCURRED DUE TO CHANCE in PSYCHOLOGY is p<0.05 (less than 5%)

This is the LEVEL at which the RESEARCHER DECIDES TO ACCEPT THE ALTERNATIVE HYPOTHESIS/REJECT THE NULL HYPOTHESIS

Question 4

when can you use a SIGN TEST?

Answer 4

There are RULES about when a PARTICULAR INFERENTIAL STATISTIC CAN BE USED

The SIGN TEST can only be used when there is ONE GROUP OF PPS (e.g a REPEATED MEASURES DESIGN) and when the DATA IS NUMERICAL (QUANTITATIVE)

Question 5

how to do SIGN TEST? - PT 1

Answer 5

1) STATE HYPOTHESIS
2) RECORD THE DATA AND WORK OUT THE SIGN OF DIFFERENCE (POSITIVE, NEGATIVE OR ZERO)
3) CALCULATE ‘S’ (CALCULATED VALUE) - ADD UP ALL THE PLUS SIGNS and ALL THE MINUS SIGNS and SELECT THE SMALLER VALUE (if there are 10 PLUSES and 3 MINUSES then S=3)

Question 6

how to do SIGN TEST? - PT 2

Answer 6

4) FIND CRITICAL VALUE - N is the TOTAL NUMBER OF SCORES (EXCLUDING ANY ZERO VALUES

Based on the HYPOTHESIS (ONE TAILED/TWO TAILED) we know which COLUMN TO USE FOR OUR CRITICAL VALUE - use the SIGNIFICANCE VALUE STATED IN THE QUESTION

The CALCULATED VALUE (S) must be EQUAL TO or LESS THAN the CRITICAL VALUE for the RESULTS TO BE SIGNIFICANT

Question 7

final step of SIGN TEST

Answer 7

If the HYPOTHESIS is ONE TAILED (DIRECTIONAL) we also have to check that the results are IN THE EXPECTED DIRECTION

If this is the case, then we can ACCEPT THE ALTERNATIVE HYPOTHESIS and REJECT THE NULL HYPOTHESIS